The Melon tree, papaya or papita (Carica papaya) belonging to the family Caricaceae seems to have been introduced into China as an Indian plant, even though this tropical plant is a native of Mexico. It came to India via Malacca in the 16th century. It has gained the greatest popularity in Hawaii.
In India there was a prejudice against this fruit in the beginning. In the Punjab, the fruit was considered to have a disagreeable odour and in South India it was considered to cause some women’s ailments. Now it has become popular all over India and is commercially the fifth most important fruit of the country. It has gained most popularity during the last 50 years.
The reasons for its rapid popularity are simple and strong. It comes to fruiting in about a year, gives the highest production of fruit per unit area and an income next to the banana. Under ideal conditions, apples and grapes give more income, but no higher yields. The yield can go upto well over 100 tonnes per hectare.
It is a nutritive fruit containing 0.5 per cent protein and an equivalent amount of minerals, consisting mainly of iron, calcium and phosphorus, 2020 international units (mango has 5,000 units) of vitamin A, 40 mg of vitamin C (ascorbic acid) per 100 gm of fruit and is rich in the enzyme papain which helps in the digestion of proteins.
A small piece of raw papaya cooked along with meat makes it very tender. The papain content of the fruit decreases rapidly as it ripens. Thus ripe papaya is not effective as a meat tenderiser. Papain is a very useful product.
It is said to remove skirt blemishes, is considered beneficial for the treatment of stomach ulcers, diphtheria and even cancer, it also has industrial uses. It is used in the clarification of beer, in the tanning industry and in the manufacture of chewing-gum.
Papaya is good source of pectin, which is extracted from green fruit. It also gives processed products like candy and tutifruity which are produced by the home industry in places like Bangalore, Jalgaon and Coimbatore.
Raw papaya is cooked as a vegetable or made into pickles. The ripe fruit and the seeds are also considered to have medicinal properties against disorders of liver, spleen and the digestive tract. Papain extracted from the unripe fruit can fetch Rs. 35000 per hectare. After the extraction of papain the scarred fruits are harvested and can fetch another Rs. 15000 per hectare.
Papaya has some characteristic features. Most other fruits are slow growing, woody perennial trees and are vegetatively propagated. Unlike these, papaya is herbaceous plant, the stem of which is usually not branched, which is raised from seed and gives fruit in about a year. It has a crown of palmately veined large leaves with very long leaf stalks.
The papaya has male, female, hermaphrodite (with male and female flowers on the same tree) and some other complex forms. The sex of the flowers on the same tree can undergo change with season, age and injury. The male flowers hang in long trusses. The female flowers and perfect flowers are borne in small clusters in the axils of leaves.
Sometimes in summer, a few small fruits are found hanging on the ends of long stalks of the clusters of male flowers. On the other hand, in Hawaii the change of sex towards femaleness is seen in the cool weather. Fruits from the perfect flowers are more elongated, angular and less attractive than those from the purely female plants.
A few male trees have to be retained in the plantation for pollination of the female flowers. In the absence of this, a few seedless fruits may develop, but these are commercially worthless. Seedlings from mixed seed give rise to plants of various sexes.
It would be desirable to identify the sex of the plants in the nursery bed so that unwanted male trees may be discarded. Many efforts and claims have been made to identify the sex of the seedlings on the basis of the appearance of the seeds, vigour of the plants and some chemical tests.
It has also been claimed that the sex of the male plants can be changed by manuring and decapitating them. None of these methods has been found practicable and some of them are baseless. However, the decapitation of the plant, if only one new shoot is retained on it, gives fruits of good quality in Florida.
If the female trees are pollinated with hermaphrodite ones, the progeny consists of only female and hermaphrodite plants. In this case, male plants, which do not bear any fruit, are not required for pollination of females. However, the hermaphrodite plants are not as productive as the female ones. So the best plan is to plant a large numbers of seedlings and uproot the male plants after flowering. This gives highest yield and income.
Papaya is a tropical plant, but it also does very well in a mild tropical climate. It is very sensitive to frost. Temperature is one of the most important factors which determine the success of papaya cultivation. Night temperature below 12° to 14°C for several hours during winter, frost and water stagnation severely affect the success of this crop.
Another type of papaya, called the mountain papaya C. candamarcensis can grow upto an elevation of 2000 metres, but it produces numerous fruits of poor quality. Papaya does not like strong, hot or dry winds. However, dry weather at the time of ripening is preferable. Under high humidity, the fruit quality is said to be inferior.
In high rainfall areas and poor drainage of soil, the cultivation of papaya is impossible due to the death of the plants caused by the collar-rot disease. However, a hardy species, C. monoica, grows in the upper Amazon basin with an annual rainfall of 375 cm. There is no frost or a hot dry period in this area. This species produces male and female flowers on the same plant. But the fruit of this species is worthless and is of no commercial value.
Papaya is grown all over India. Even in Rajasthan, where both frost and hot winds are found, it is grown in sheltered places. In Jaipur city, papaya is seen growing in small fields enclosed in three metre high stone walls.
Papaya ranks seventh in area of production, occupying 0.73 lakh hectare. The production is 259.0 lakh tonnes, which shares 6.0% of the major fruit production in India. India is also number one producer of papaya (42.5%) in the world. The increase in both area and production has been due to the development of improved varieties of high yield and quality.
It grows in various types of soil. The most important consideration is that the soil should be well drained. Light soils are very good for papaya, if they are adequately manured. Sticky and calcareous soils, where rain water may accumulate even for a few hours are not good.
Papaya is normally propagated from seed all over the world. The seeds should be rubbed with wood ash and dried before storage. The time of sowing the seeds is important and depends upon the choice of fruiting season and danger of rain or frost. In North India, seeds are sown from February to April. “Damping off” is the most serious disease in the nursery. Treating the seed with 0.1 per cent Monsoan (phenyl mercury acetate), Ceresan, Agrosan or Thirum dust before sowing prevents this disease.
Treating the nursery beds with 5 per cent formaldehyde solution before sowing is also useful. Papaya seedlings are now-a-days raised in polythene bags which stand better transportation as compared to those raised in seed beds. Perforated polythene (150-200 gauges) bags of 20 x 15 cm size are used as container. The bags are filled with mixture containing FYM, soil and sand in equal proportion.
The seeds are sown one and half cm deep on raised beds. The distance between rows is 10 cm. The distance from seed to seed in the rows should also be the same; otherwise the seedling will have to be transplanted very soon. The seeds germinate in three to four weeks. The seed beds are protected from rain and strong sun with a cover of thatch.
About 400 to 500 g of seed is enough to give plants for one hectare. Vegetative propagation by cutting is possible. The cuttings root well after treatment with three to five per cent IBA (Indole butyric acid). However, they give weak plants. These methods have little value in commercial cultivation. Probably seed propagation imparts vigour to the plants, which have a tendency to become senescent after a few years. Propagation by tissue culture has also given some success.
The seedlings are transplanted after two months, when they have four to five leaves. June is a good month for transplanting. If irrigation during summer is plentiful, earlier planting is desirable. As a result of this, the plants are larger when winter comes and are able to withstand frost better.
In central India, papaya flowers throughout the year and fruit can be had at any time during the year except the monsoon months, July to October. So the planting time is more flexible. In this area, the seeds are sown in the rainy season. Transplanting in December gives fruits on plant when they are much shorter.
Papaya is often planted as a filler tree between newly planted mango and orange trees. It is planted two to three metres apart. Closer planting gives protection against frost and hot winds and checks the growth of weeds. However, this practice requires more manuring and irrigation. Large planting pits are not required for papaya. Papaya will grow even without previously dug pits. The pit is useful while adding manure to it.
The size of the pit is generally 1/2 metre x 1/2 metre. The top soil from the pit is mixed with about 20 kg of farmyard manure, 1 kg neem cake and 1 kg bone-meal or fishmeal and filled back into the pit. Watering in the nursery should be stopped one week prior to transplanting which helps better survival in the field. The larger leaves of the seedling are cut off at the time of transplanting.
The seedlings are normally transplanted with a ball of earth, but in South India they can be transplanted even with bare roots on a cloudy day in the rainy season. The seedlings should not be planted too deep in the soil. If a part of the stem is buried in the soil, it is more likely to be affected by collar-rot later on. At the site of each pit three seedlings are planted about 15 cm apart.
The spacing of 1.8 x 1.8 m is normally followed for most of the cultivars. A close spacing of 1.33 x 1.33 m (5609 plants/ha) has been reported to be optimum for Coorg Honey Dew papaya under Bangalore condition. The dwarf cultivars like Pusa Delicious give higher yield at a spacing of 1.4 x 1.4 m or 1.4 x 1.6 m under subtropical conditions of Bihar and at 1.6 x 1.6 m spacing in Tamil Nadu. A closer spacing of 1.2 x 1.2 m for Pusa Nanha has been advocated requiring 6400 plants/ha.
The plants flower in about 10 months in North India and in five in the South. At this stage all male plants are uprooted, leaving about 10 to 15 per cent male population in the field.
Papaya is a shallow rooted plant, which should not be given deep tillage. Only the removal of weeds at the young stage is important. The cultivation should be frequent and light. However, it requires heavy manuring and irrigation since the growth is so quick and the crop produced is heavy.
Maintenance of optimum soil moisture is essential for growth, yield and quality of fruit. Deficient moisture level favours female sterility resulting in low productivity. At the same time, over irrigation can cause root rot disease.
Irrigation should be given every 10 days in winter and every week in summer, provided there is no rain. When there is danger of frost, irrigation is useful. Irrigation should be done by the ring method, which is followed in Gujarat and prevents the water from coming in contact with the stern.
Papaya is a heavy feeder. Hence, adequate fertilizers should be applied. Apart from the basal dose of manure applied in the pits, invariably 200 to 250 g each of N, P and K per plant is recommended for getting good yield. Application of super phosphate and potash improves the yield as well as fruit quality.
At I.I.H.R., Bangalore 240 g N, 500 g P and 500 g K plant/year gave the best results for Coorg Honey Dew papaya. While at Coimbatore 200 g each of N, P and K in addition to 25 kg FYM in split dose at the first, third, fifth and seventh month after planting are recommended for Co-1 papaya. However, in the alluvial soil of West Bengal, papaya cv. Ranchi has best results by the application of 200 g N, 300 g P and 600 g K/ plant/ year in three split doses at 30, 60 and 120 days after transplanting.
If necessary, trenches are made between the rows of plants during the monsoon season so that rain water does not stagnate in the field. Thinning of fruits when they are about 2 cm long, gives large fruits of regular shape. The operation should be performed frequently. The extent of thinning should be such that the fruits do not touch one another when mature. Too much thinning reduces yield.
Unfruitfulness in papaya has been observed in many places. It is mainly due to lack of proper pollination. Coorg Honey Dew performs well in South India especially in Karnataka but is a poor yielder in North India. Variety Ranchi is suitable for the Ranchi area.
Similarly, successful varieties in other regions are Barwani in central India, Washington in Western India, “Co” varieties in Southern India. Exotic varieties like Taiwan, Solo, Sunrise Solo and Thailand perform well in Southern and Western India but give poor performance in North India. Thus, only established varieties suitable for a specific area should be grown.
Papaya is cross pollinated crop and has many sex forms. Several sex forms have given rise to numerous varieties. Since papaya is propagated by seed, which is not produced under controlled conditions, the identity of the different varieties is not clear cut. Probably the only old well-established papaya variety in the world is the Solo, which has been in cultivation in the Hawai Islands.
It produces plants with only female and perfect flowers (gynodioecious) and performs well under South Indian condition. The variety Honey Dew or Madhu Bindu in India is said to come fairly true to type from seed and has a small proportion of male plants. It bears fruit low on the trunk, the yield is heavy and it has elongated fruits with comparatively few seeds. A selection made from this, the Coorg Honey Dew produces only female and hermaphrodite (gynodioecious) plants and no pure male plants.
The variety Washington also comes fairly true to type from seed. It has yellow flowers, dark purple petioles of leaves, purple ring on the stem and dwarf plant. This is an important cultivar of Maharashtra for papain extraction. Barwani from Indore is of good quality and bears well in North India However; it shows wide variation and has fruits with deep orange as well as yellowish flesh.
Pusa (IARI) Varieties:
1. Pusa Delicious – A gynodioecious cultivar, in which there is no need to plant two-three plants in a pit to ensure that at least one of them is productive, medium sized fruit excellent fruit taste and good flavour.
2. Pusa Majesty – This is also gynodioecious variety with high productivity and better keeping quality. It is high papain yielder and is resistant to nematodes.
3. Pusa Dwarf – Dwarf stature, dioecious, fruits oval in shape, precocious and fruits of medium size.
4. Pusa Nanha (mutant) – Exceptionaly dwarf variety, suitable for Kitchen garden, pot and roof top cultivation. Ideal variety for high density orchard.
Coimbatore Varieties:
1. Co-1 – Selection from cultivar Ranchi, dwarf, dioecious, fruit round to oval with orange colour flesh.
2. Co-5 – Inbred selection from Washington, mainly used for papain production.
3. Co-6 – Selection from Pusa Majesty, dioecious, dwarf stature, fruits large sized, good for papain and dessert purposes.
4. Co-7 – Gynodioecious, flesh red colour, fruits of uniform size and improved quality.
Bangalore (IIHR) Varieties:
1. Pink Flesh Sweet – A selection made with excellent fruit quality, high TSS (12 to 14) content.
2. Hybrid-39 – Hybrid between Sunrise solo and Pink Flesh-Sweet, gynodioecious and excellent fruit quality.
3. Hybrid-54 – Hybrid between Waimanalo Χ Pink Flesh Sweet, gynodioecious, fruit is sweet with longer shelf life.
Exotic Varieties:
1. Sunrise Solo – Gynodioecious variety from Hawaii, pink flesh colour and good taste.
2. Taiwan – Gynodioecious variety with blood red flesh colour and good taste.
3. Thailand – Gynodioecious variety, having deep red flesh colour, sweet taste, and high yielding.
All the exotic varieties having deep red or pink flesh colour with few seeds are often called in the market as “Disco papaya”.
In North India, harvesting starts from December, about 16 to 18 months after planting and lasts four to five months. In Central and South India, the crop starts from February. It takes about six months to flower and another five months for harvesting. The fruits ripened on the tree have the best quality.
For distant markets, the fruits are harvested when they have developed full size, light green colour with tinge of yellow at the apical end and the latex ceases to be milky and becomes watery.
While picking the fruits from the tree, care must be taken that they are not scratched and are free from any blemishes, otherwise there will be attack of fungus and fruits may start decaying during marketing.
The yield per tree in India varies from 20 to 150 fruits per annum. The average weight of a fruit should be at least one kilogram. However, on an average each plant of improved varieties bears 30 to 45 fruits weighing upto 40 to 75 kg in one fruiting season. An average yield of 60 to 75 tonnes/ha can be expected in a season.
The fruit can be ripened well by treatment with one part of ethylene gas in 5000 parts of air, but this is not practiced in India.
Papaya has no serious insect pests, it has some serious diseases. The most serious disease is the collar or foot rot, caused by a soil borne fungus (Pythium aphanidermatum). During the rainy season it causes swelling, cracking and rotting of the stem, where it comes in contact with water. It is hard to prevent or cure, but can be checked by three sprays of 6-6-50 Bordeaux mixture during the rainy season and drenching the soil around the stem with the same mixture or Vapum.
The infected portion on stem should be cleaned and pasted with Bordeaux paste (5:5:20). Root rot in papaya may be caused by fungus Rhizoctonia solani or Fusarium sp. No specific control measure is available. Application of one kilogram lime and 100 g CuSO4 in the pits before planting can reduce the root rot problem.
These fungi can also kill young seedlings in the nursery. This can be prevented by sterilization of the nursery bed with formaldehyde (two weeks before seed sowing) or treating the seeds with Captan, Ceresan or Agrosan. Anthracnose, leaf spot, fruit rot and powdery mildew are also found.
Bud and fruit stalk rot of papaya is another recently discovered fungal disease (Fusarium solanai) which affects stalk and newly set fruits, which drop off. Prophylactic spray of Bordeaux mixture checks this disease.
Leaf curl is common in North India, especially where drainage of the soil is poor. The leaves of the plants become wrinkled and the plants remain stunted. The virus mosaic and Distortion Ring spot are also prevalent. Necrotic dots are seen on the leaves. The lamina becomes yellowish green, malformed, upright and with blistered patches on it.
Fruiting is also affected. It can be minimized by delayed planting i.e. after rainy season. Spraying suitable insecticides against vector checks further spread of viruses. The virus affected plants should be quickly destroyed to prevent the spread of these diseases, since no cure is known.
The insect pests of papaya are not serious. The most important, is the red spider mite. It can be controlled by spraying lime sulphur. The caterpillar, Dasyses rugosellus, and root knot nematodes have also been found. Birds are the most serious pests of papaya. Bird scaring is an important item of expenditure in the cultivation of this crop.